Zero DC-Bus Voltage Occupation Variable Amplitude Signal Injection Method for IPMSM Sensorless Control Through Maintaining Current Sampling Noise Stationarity

The variable amplitude pulsating signal injection sensorless method for IPMSMs significantly reduces the DCbus voltage occupancy of the injection voltage and expands the operational speed range. However, the estimation accuracy is degraded by the amplified current sampling noise, which limits further reduction of voltage occupancy. To improve performance, an estimator with a forward prediction-feedback-state update structure is proposed to maintain the noise stationarity from current sampling to estimation results, where time-variant uneven amplifications of noise are removed in the closed-loop forward path. First, the estimated response currents are reconstructed based on the injection voltage and the instantaneous susceptances determined by the estimated rotor position and the estimated dq-axes inductances. Then, the estimated currents are compared with the noised sampled response currents for feedback estimation, thereby driving the estimated rotor position and the estimated dq-axes inductances to converge to the actual value. Experimental results validate the effectiveness of the proposed method, showing 70% lower noise in extracted position and speed compared to conventional approaches. This method inherently enables zero DC-bus voltage occupancy and thus achieves the same operational range as sensor-based position control systems, from standstill to rated and field-weakening conditions.